Comparison of Overall Fit of Milled and Laser-Sintered CAD/CAM Crown Copings

Abstract

Background and Aims. The aim of this study was to investigate the effect of computer-aided design/computer-aided manufacturing (CAD/CAM) procedures on the overall fit of metal copings. Materials and Methods. A standardized die was made in die stone of an upper right molar prepared for a full crown. The die was digitalized by an Identica Blue Light Scanner, and the coping substructure was designed using CAD software. Ten milled specimens and ten laser-sintered specimens were manufactured by Renishaw plc based on the generated file by the software. All twenty copings were digitized by the Identica scanner, and the data were superimposed with the original premanufacturing data file of the prepared full crown. Using the Geometric Modelling Library (GML) package, the fit discrepancies were displayed as colour maps showing discrepancies in three dimensions. Each map was made up of thousands of data points carrying numerical error values allowing detailed analyses. Results. The milled group displayed a mean of fit discrepancies of 42.20 μm (SD 3.04 μm), while the laser-sintered group showed a mean of 42.24 μm fit discrepancies (SD 2.94 μm). Thus, a small difference of 0.04 μm between the two groups was detected. Conclusions. The evaluated manufacturing systems can be used in dental practice as a small and insignificant discrepancy of fit between the two manufacturing methods was detected.